The present invention relates generally to motors and, more particularly, to a motor for a vacuum cleaner assembly and a method for starting and operating the same.
Electric motors are used in a variety of applications. One such application is vacuum cleaners.
Vacuum cleaners of various designs are used in residential and commercial settings for a wide variety of cleaning purposes. These appliances develop suction force to create air flow which picks up large and small dust and dirt particulates from the surface being cleaned. These particulates are then separated from the ingested air within the vacuum cleaner for later disposal. One type of vacuum cleaner is a canister type which has a relatively stationary canister which is connected to a moveable wand by a flexible connecting hose. One particular design of canister type vacuum cleaner is known as a liquid bath type. This type of vacuum cleaner directs incoming air and particulates into contact with a liquid bath, which is typically water, which traps particulate matter such as dust and dirt particles entrained in the ingested air stream as the air stream impinges the surface of the liquid. A liquid bath type vacuum cleaner has a significant advantage in that its filtration mechanism is water, thereby eliminating the need for replacement filters. Accordingly, only the water in a liquid reservoir needs to be periodically changed.
An important component of all liquid type vacuum is the motor. Typically, the motor is of the type generally known as a universal motor. The motor converts electrical energy into kinetic energy, i.e., electrical energy is transferred through a pair of brushes to an armature, causing the armature to rotate.
One drawback of this type of motor is that it is prone to wear, resulting in mechanical breakdowns.
Brushless motors have certain advantages over these types of motors. There is simply not the wear and tear on the motor due to the brushes. However, typical one- and two-phase brushless motors are hard to start and the typical starting process is inefficient and causes wear and tear.
One type of brushless motor is the switched reluctance motor. Switched reluctance motors have a rotor and a stator. The stator includes windings which are energized in order to provide torque to the rotor, Previously, switched reluctance motors have had either the same number of poles on the stator and the rotor or are designed with more stator poles than rotor poles. The conventional wisdom was that additional stator poles reduce ripples in the torque applied to the rotor. Torque ripple is the variation in maximum available output torque as the position of the rotor poles varies with respect to the stator poles. However, the tradeoff with the additional stator poles is decreased efficiency.
The present invention is aimed at one or more the problems set forth above.
It is an object of the present invention to provide a motor having lower torque ripple and improved starting torque thereby resulting in less wear and tear on the motor and increased efficiency.
The vacuum cleaner assembly of the present assembly includes a housing assembly having an inlet port, an outlet port and a plurality of components, a motor having a rotor and a stator disposed in the housing for providing motive power to the plurality of components. The rotor includes a plurality of rotor armatures each with a rotor tip and the stator includes a plurality of stator armatures each with a stator tip. The vacuum cleaner assembly of the present invention further includes a blower assembly disposed in the housing assembly which is driven by the motor for drawing air inwardly through the inlet port and exhausting air outwardly through the outlet port. A separator is disposed in the housing assembly for filtering air drawn inwardly through the inlet port before it is exhausted through the outlet port.
In one aspect of the present invention, the rotor tips have a width different than the width of the stator tips. In another aspect of the present invention, the rotor armatures have a non-constant width. In yet another aspect of the present invention, the motor is a two-phase brushless motor wherein the stator includes an even number (N) of stator armatures and the rotor includes N+2 rotor armatures. In still another aspect of the invention, the motor includes a rotor with at least one of the rotor armatures having an aperture therein for creating an imbalance in the magnetic flux generated by the stator. According to another aspect of the vacuum cleaner assembly of the present invention, each of the rotor armatures includes a plurality of layers laminated together, with one of the plurality of layers having dimensions different than other of the plurality of layers.
A second embodiment of the vacuum cleaner assembly of the subject invention, includes a control circuit for controlling the motor to alternately energize a first pair of windings for attracting a first set of the permanent magnets and causing the rotor to rotate in a first direction and a second pair of the windings for attracting a second set of the permanent magnets and causing the rotor to continue to rotate in the first direction. In another aspect of the present invention, the control circuit is adapted for energizing the first pair of the windings for attracting the first set of permanent magnets and causing the rotor to rotate in a second direction prior to alternately energizing the first and second pairs of windings to rotate the rotor in the first direction. In yet another aspect of the present invention, the control circuit is adapted for measuring the motor temperature and comparing the motor temperature with a predetermined temperature for reducing the constant power delivered to the motor when the motor temperature exceeds the predetermined temperature. According to another aspect of the present invention, the control circuit is adapted for shutting down the motor when the motor temperature exceeds the predetermined temperature.